Cardiac transplant patients have been shown to suffer rapid bone loss in the first six to twelve months after transplantation. A recently released aminobisphosphonate, alendronate, has been shown to be effective in significantly increasing bone mass in postmenopausal osteoporotic women. There are presently no data regarding the effects of alendronate on steroid induced osteoporosis. We will treat 15 cardiac transplant patients with alendronate and 15 with placebo. Bone densitometry and markers of bone turnover will be assessed serially over a 12-month period.